Boiling water reactor plant

ABSTRACT

The socket serves as an inlet for feed water and as a housing for the turbine shaft which drives the pump. The socket includes a duct which delivers feed water directly into the water chamber as well as a duct for feeding the water discharged from the turbine into the water chamber via the pump.

United States Patent 1191 Florjancic 1 1 Feb. 6, 1973 1 1 BOILING WATERREACTOR PLANT [751 lnventor: Dusan Florjancic, Winterthur, Switzerland[73] Assignee: Sulzer Brothers Ltd., Winterthur,

Switzerland [22] Filed: June 28,197]

[21] App]. No.1 157,437

[30] Foreign Application Priority Data July 1, 1970 Switzerland..996l/7O [52] 11.8. Cl. ..l76/54, 417/406, 176/87 [51] Int. Cl. ..G2lc15/24 [58] Field of Search ..176/54,55,56,6l,65,87;

[ 56] References Cited UNITED STATES PATENTS 3,231,474 l/l966 Jones etal 176/56 X 3,279,384 10/1966 .lekut et al. ..4 1 7/406 X 2,873,9452/1959 Kuhn 1 ..4l7/406 3,102,490 9/1963 Shiley t ..4l7/406 X 3,171,3553/1965 Harris et al. 1 i l ..4l7/406 X 3,203,867 8/1965 Williams et a1.1 76/65 X 3,401.082 9/1968 Ammon et al ..l76/54 FOREIGN PATENTS ORAPPLICATIONS 966,743 8/1964 Great Britain ..176/65 PrimaryExaminer-Benjamin R. Padgett Assistant Examiner-E. E. LehmannAttorney-Kenyon & Kenyon Reilly Carr & Chapin [57] ABSTRACT The socketserves as an inlet for feed water and as a housing for the turbine shaftwhich drives the pump. The socket includes a duct which delivers feedwater directly into the water chamber as well as a duct for feeding thewater discharged from the turbine into the water chamber via the pump.

13 Claims, 5 Drawing Figures PATENTEDFEB 6 $75 SHEET 2 OF 5 PATENTEUFEBe 1975 SHEET '4 [IF 5 PATENTEU FEB 5 I975 SHEET 5 0F 5 Fig.5

noruNc WATER REACTOR PLANT This invention relates to a boiling waterreactor plant.

Boiling water reactor plants have been known in which a circulating pumpfor circulating water within a water chamber of a pressure vessel hasbeen driven by a water turbine which has been operated with feed water.This provides an advantageous construction by virtue of the fact thatcomplicated seals between the circulating pump and the drive for thepump may be omitted.

The object of this invention is to provide a plant which is simpler andmore reliable than previous plants of this kind.

Briefly, the invention provides'a boiling-water reactor plant which ischaracterized in that the water turbine is disposed on a connectingsocket situated in known manner below the water level in the pressurevessel but disposed above the reactor core. In addition, the drivingshaft for the circulating pump is brought through the socket and atleast one duct is provided in the socket for introducing feed waterdischarged from the turbine into the water chamber of the reactor.

The invention enables a minimum number of connecting sockets on thepressure vessel to be used. Further, connecting sockets, which areotherwise provided on the pressure vessel of the reactor for the supplyof feed water, may be used for the driving turbines and their shafts.

The connecting sockets are disposed above the reactor core and near thewater level of the water chamber to enable the thermo-siphon effect ofthe colder feed water to be utilized. With respect to the circulatingpumps, this feature provides the advantage that the water level need belowered only below the level of the circulating pump for the purpose ofrepairs to be carried out to the turbine or to the pump. Thus, thereactor core may remain under water. The absence of additionalconnecting sockets for the turbine also plays an important part sincethe production of the connecting sockets is expensive and since theirpresence represents hazardous zones of the pressure vessel as they aresubject to complex stress conditions and usually require welding seamswhich can be controlled only with a great effort.

In one embodiment, the impeller of the circulating pump is sized so asto be removed outwardly through the connecting socket. In particular,this substantially facilitates the previously mentioned repair ofacirculating pump.

In another embodiment, the connecting socket also has a duct for thesupply of feed water into the water chamber of the reactor whichbypasses the turbine. As a result, this dispenses with the need forseparate apertures or sockets in the pressure vessel. In somecircumstances, it is possible for the duct in the connecting socket tobe the same duct which carries the feed water discharged from theturbine.

In another embodiment, the feed water is admixed to the circulating flowin the pressure vessel within the circulating pump. This feature enablesa particularly simple embodiment to be obtained which in somecircumstances offers further advantages. For example, by admixingupstream of the pump impeller, it is possible for the water flowingthrough the pump to be cooled, thus increasing the available thermalsuction head since the vapor pressure of the circulated water is loweredat this position.

In another embodiment, the circulating pump is provided with diffuserblades on the inlet side. These diffuser blades are further providedwith ducts which extend outwardly into the delivered flow and areconnected to the ducts for supplying the feed water. In such a system,simple means provide very uniform intermixing of the feed water with thecirculating flow. This is advantageous for the previously mentionedpurpose ofincreasing the suction head of the pump.

In a particularly advantageous embodiment, the impeller of thecirculating pump is provided with ducts formed in the blades. Theseducts extend outwardly into thedelivered flow and are connected to theduct for introducing feed water so as to form a laminar flow of feedwater along the surface of the blade. This results, in a particularlyeffective manner, in an increase of the suction head of the pump sincethis achieves a targeted cooling of those zones of the pump at whichthere is a risk of vapor bubble formation. The remaining feed water maybe introduced into the diffuser of the circulating pump, that is,downstream of the impeller. Accordingly, the feed water is not conductedthrough the pump so that the pump may be constructed to smallerdimensions.

These and other objects and advantages of the invention will become moreapparent from the following detailed description and appended claimstaken in conjunction with the accompanying drawings in which:

FIG. 1 diagrammatically illustrates a cross-sectional view through aboiling-water reactor with the circulating pumps disposed in accordancewith the invention;

FIG. 2 illustrates a cross-sectional view of one embodiment of acirculating pump for the reactor according to FIG. 1;

FIG. 3 illustrates a cross-sectional view of another embodiment of thecirculating pump together with its drive according to the invention.

FIG. 4 illustrates a crosssectional view of a particularly advantageousembodiment of the circulating pump and its drive for a nuclear reactoraccording to FIG. 1; and

FIG. 5 illustrates a cross-sectional view of a modified embodiment ofthe circulating pump of FIG. 3 according to the invention.

Referring to FIG. 1, a boiling-water reactor has a pressure vessel Idefining a water chamber, a reactor core 2, a steam trap 3 and aplurality of circulating pumps 4 which are disposed below the waterlevel 5 in the vessel 1 but are disposed above the reactor core 2. Theshafts of the circulating pump impellers (not shown) extend throughconnecting sockets 6 on which the casing 7 of water turbines are mountedfor driving the impellers of the pumps 4. The casings 7 contain pipeconnections 8 and 9, both of which are provided for the supply of feedwater. One of these connections serves for the supply of feed water fordriving the turbines while the other connections serve for the directsupply of feed water into the reactor while bypassing the turbines. Thearrows in FIG. 1 indicate the flow directions of the circulating flow inthe water chamber of the reactor and that of the feed water.

Referring to FIG. 2, wherein like reference characters indicate likeparts as above, the water turbine casing 7 is closed by a cover 10 andhouses turbine elements 11, as are known, a bearing 12 for a shaft 13and a rotor 14. The other end of the shaft 13 is supported in a bearing15 in a pump casing 16 and serves to support an impeller 17. Upstream ofthe impeller 17, as seen by reference to the flow direction of thecirculated water, the pump casing 16 is provided with stationarydiffuser blades 18 each of which has a bore 20 and bores 21 disposedtransversely thereto and extending outwardly. As shown, the-bores 20 ofeach blade 18 extend across the blade 18 while the bores 21 extend tothe free edge of the blade 18.

As indicated by the arrow P in FIG. 2, the feed water discharged fromthe rotor 14 of the turbine flows through an annular chamber 22 aboutthe shaft 13 into a surrounding annular chamber 23 associated therewithand disposed in the connecting socket 6. The annular chamber 23 is alsoconnected at one end to the supply duct 9 for the feed water and at theopposite end to the bores 20 in the diffuser blades 18 of the pump 4.During operation, the feed water discharged from the rotor 14 of theturbine or supplied through the duct 9 passes from the annular chamber23 into the bores 20 of the blades and from there through the bores 21into the circulating flow conducted through the pump 4.

As shown, the connecting sockets 6 provide for the mounting of thedriving turbines for the circulating pumps 4 as well as for the supplyof feed water. Accordingly, the need for separate sockets for thedriving shafts of the circulating pumps together with their seals isavoided. An additional advantage is obtained in that the circulatingflow in the pump is cooled by the admixture of cooler feed water so thatthe risk of vapor bubbles, which result in a deterioration of thesuction effect in the pump, are avoided. This is particularly importantin the case illustrated in FIG. I, in which the circulating pumps aredisposed above the reactor core and below the water level 5. At thisposition, the circulating pumps have only a very low inlet head; thisposition being advantageous for operational reasons since it is merelynecessary to lower the water level in the reactor to enable the pumps tobe dismantled. The illustrated embodiment suppresses the generation ofvapor bubbles and as a result of this feature in some cases, only forthe first time, permits correct functioning of the circulating pumps.

Referring to FIG. 3 wherein like reference characters indicate likeparts as above, the casing of a pump 30 is reversed relative to thecasing of the pump 4 of FIG. 2 so that the pump position corresponds tothat illustrated in FIG. 1. In this embodiment, the rotor 14 of theturbine is mounted on a hollow shaft 31 having a bore 32. The feed watercan thus pass from the duct 8 while bypassing the turbine through thebore 32 into a casing part 33 of the circulating pump 30. In this case,the casing of the pump 30 is provided with stationary diffuser blades 34having bores 35, 36. The bores 35 extend across the blades 34 while thecommunicating bores 36 extend to the surface of the blades 34. The feedwater, flowing through the rotor 14 of the turbine, also reaches thecasing part 33 through an annular chamber 37. From the casing part 33,the feed water flows through the ducts 35 and 36 outwardly and isadmixed to the circulating flow upstream of the impeller 38 of thecirculating pump. The method of operation and action of the embodimentaccording to FIG. 3 are identical in all other respects to those of theembodiment illustrated in FIG. 2 and need not be further detailed.

Referring to FIG. 4 wherein the left-hand part of the construction withthe socket 6 and the driving turbine is identical to the embodimentillustrated in FIG. 2 and is designated with the same referencecharacters, a pump 40 which is disposed in a manner similar to thatillustrated in FIG. 3, contains an impeller 41 having ducts 42, 43 and44 which extend from the eye of the impeller 41 into the blades and fromthere outwardly. The ducts 42, 43, 44 are connected to an axial bore orduct 45 of the shaft 13 which is supplied through a radial bore 46 withfeed water discharged from the rotor 14 of the turbine. In addition, thepump 40 is provided with a diffuser 47 having separate flow ducts 48, 49for the circulating flow and for the feed water supplied thereto.

In operation, the feed water is admixed to the circulating flow onlydownstream of the impeller 41 of the circulating pump 40. Only a smallerquantity of water is required for recirculation so that the pump and,therefore the driving turbine, may be constructed in a smaller size.However, the advantageous effect of cooling due to the flow through thepump is thus omitted. Accordingly, the ducts 42 .to 44 are formed in theimpeller 41 to supply cool feed water into the blades. The feed waterdischarged outwardly from the ducts 44 forms a laminar flow, extendingalong the surface of the blade and this directly cooling the zone inwhich there is a risk of vapor bubble formation. A smaller amount ofcooling water in the form of feed water is required in this constructionto achieve the same effect as regards the suppression of vapor bubbles.

The inlet sockets of the circulating pumps according to FIGS. 2, 3, and4 may be axially symmetrical solids of rotation or, according to thedrawing in FIG. 1, they may form inlet funnels which are open only atthe top. A construction with one axial inflow is also possible as shownin FIG. 5.

Referring to FIG. 5 which represents a modified embodiment of thearrangement illustrated in the righthand part of FIG. 3, the pump 3contains a suction socket 50 having a hollow inner member 51. The cavityof the member 51 is connected to the bore 32 of the hollow shaft 31.Diffuser blades 53 are disposed between the inner member 51 and an outerjacket 52. These diffuser blades have radial bores 54 communicating withthe cavity of the member 51 and adjoining outwardly extending bores 55through which the feed water, supplied through the ducts 32 and 37 maybe admixed to the circulating flow delivered through the pump 30.

It will be evident that in the embodiment illustrated in FIG. 4 as wellas in the embodiment illustrated in FIGS. 2 and 3, it is possible fordifferent methods of cooling the blades or of the flow passing by theblades to be employed. For example, methods as proposed in US Pat.application, Ser. No. l57,438, filed June 28, l97l can be used.

As can be seen by reference to FIGS. 2 to 5, the pump in all embodimentsis constructed so that removal of the casing 7 simultaneously enablesthe shaft 13 or 13', 32 to be removed together with the impeller of thecirculating pump. Only the pump casing with the inlet socket, thediffuser blades and the diffuser remains in the pressure vessel. Thismeasure substantially facilitates any repairs of the pump impeller whichmay become necessary.

What is claimed is:

1. A boiling water reactor plant comprising a pressure vessel defining awater chamber for a level ofwater therein;

a reactor core disposed in said chamber below the level ofwater withinsaid chamber;

at least one circulating pump in said vessel having an impeller forcirculating water through said pump;

a connecting socket secured to said vessel below the level of water andabove said reactor core;

a driving shaft. connected to said pump for driving said impeller ofsaid pump, said shaft passing out of said vessel through said socket;

a water turbine mounted on said socket and connected to said drivingshaft outside said vessel for driving said shaft;

means for passing a flow of feed water through said turbine for drivingsaid turbine;

at least one duct in said socket for receiving feed water dischargedfrom said turbine and for introducing the discharged feed water intosaid pump; and

means connected to said duct for admixing feed water supplied from saidduct with a circulating flow of water in said pump upstream of saidimpeller.

2. A boiling water reactor plant as set forth in claim 1 wherein saidimpeller is of a size smaller than the internal periphery of said socketfor passage therethrough upon dismantling of said pump. v

3. A boiling water reactor plant as set forth in claim 1 furthercomprising at least one duct in said socket bypassing said turbine forsupplying feed water into said water chamber.

4. A boiling water reactor plant as set forth in claim 1 wherein saidpump has a plurality of diffuser blades on an inlet side thereof, andsaid admixing means includes bores within each blade extending outwardlythereof into the circulating flow, said bores being connected to saidduct in said socket for discharging feed water from within said bladesinto the circulating flow.

5. A boiling water reactor plant as set forth in claim 1 wherein saidadmixing means includes bores within said impeller extending outwardlythereof into the circulating flow, said bores being connected to saidduct in said socket for discharging feed water from within said impelleronto the surface of said impeller to form a laminar flow of feed waterthereon.

6. A boiling water reactor plant as set forth in claim 1 wherein saidpump has a diffuser downstream of said impeller and said socket includesa duct for introducing feed water into said diffuser from said socket.

7. A boiling water reactor plant as set forth in claim 1 wherein saidduct is disposed axially within said shaft.

8. A boiling water reactor plant comprising a pressure vessel defining awater chamber for a level of water therein;

a reactor core disposed in said chamber below the level of water withinsaid chamber;

at least one circulating pump in said vessel having an impeller forcirculating water through said pum a connecting socket secured to saidvessel below he level of water and above said reactor core;

7 a driving shaft connected to said pump for driving said impeller ofsaid pump, said' shaft passing out of said vessel through said socket;

a water turbine mounted on said socket and connected to said drivingshaft outside said vessel for driving said shaft;

means for passing a flow of feed water through said turbine for drivingsaid turbine; and

at least one duct in said socket for receiving feed water dischargedfrom said turbine and for introducing the discharged feed water intosaid pump upstream of said impeller.

9. A boiling water reactor plant as set forth in claim 8 wherein saidimpeller of said pump is of a size smaller than the internal peripheryof said socket for passing therethrough upon dismantling of said pump.

10. A boiling water reactor plant as set forth in claim 8 furthercomprising at least one duct in said socket bypassing said turbine forsupplying feed water into said water chamber.

11. A boiling water reactor plant as set forth in claim 8 furthercomprising means for admixing feed water supplied through said socketwith a circulating flow of water in said pump.

12. A boiling water reactor plant as set forth in claim 11 wherein saidpump has a plurality of diffuser blades on an inlet side thereof, andsaid admixing means includes bores within each blade extending outwardlythereof into the circulating flow, said bores being connected to saidduct in said socket for discharging feed water from within said bladesinto the circulating flow.

13. A boiling water reactor plant as set forth in claim 11 wherein saidadmixing means includes bores within said impeller extending outwardlythereof into the circulating flow, said bores being connected to saidduct in said socket for discharging feed water from within said impelleronto the surface of said impeller to form a laminar flow of feed waterthereon.

1. A boiling water reactor plant comprising a pressure vessel defining awater chamber for a level of water therein; a reactor core disposed insaid chamber below the level of water within said chamber; at least onecirculating pump in said vessel having an impeller for circulating waterthrough said pump; a connecting socket secured to said vessel below thelevel of water and above said reactor core; a driving shaft connected tosaid pump for driving said impeller of said pump, said shaft passing outof said vessel through said socket; a water turbine mounted on saidsocket and connected to said driving shaft outside said vessel fordriving said shaft; means for passing a flow of feed water through saidturbine for driving said turbine; at least one duct in said socket forreceiving feed water discharged from said turbine and for introducingthe discharged feed water into said pump; and means connected to saidduct for admixing feed water supplied from said duct with a circulatingflow of water in said pump upstream of said impeller.
 2. A boiling waterreactor plant as set forth in claim 1 wherein said impeller is of a sizesmaller than the internal periphery of said socket for passagetherethrough upon dismantling of said pump.
 3. A boiling water reactorplant as set forth in claim 1 further comprising at least one duct insaid socket bypassing said turbine for supplying feed water into saidwater chamber.
 4. A boiling water reactor plant as set forth in claim 1wherein said pump has a plurality of diffuser blades on an inlet sidethereof, and said admixing means includes bores within each bladeextending outwardly thereof into the circulating flow, said bores beingconnected to said duct in said socket for discharging feed water fromwithin said blades into the circulating flow.
 5. A boiling water reactorplant as set forth in claim 1 wherein said admixing means includes boreswithin said impeller extending outwardly thereof into the circulatingflow, said bores being connected to said duct in said socket fordischarging feed water from within said impeller onto the surface ofsaid impeller to form a laminar flow of feed water thereon.
 6. A boilingwater reactor plant as set forth in claim 1 wherein said pump has adiffuser downstream of said impeller and said socket includes a duct forintroducing feed water into said diffuser from said socket.
 7. A boilingwater reactor plant as set forth in claim 1 wherein said duct isdisposed axially within said shaft.
 8. A boiling water reactor plantcomprising a pressure vessel defining a water chamber for a level ofwater therein; a reactor core disposed in said chamber below the levelof water within said chamber; at least one circulating pump in saidvessel having an impeller for circulating water through said pump; aconnecting socket secured to said vessel below the level of water andabove said reactor core; a driving shaft connected to said pump fordriving said impeller of said pump, said shaft passing out of saidvessel through said socket; a water turbine mounted on said socket andconnected to said driving shaft outside said vessel for driving saidshaft; means for passing a flow of feed water through said turbine fordriving said turbine; and at least one duct in said socket for receivingfeed water discharged from said turbine and for introducing thedischarged feed water into said pump upstream of said impeller.
 9. Aboiling water reactor plant as set forth in claim 8 wherein saidimpeller of said pump is of a size smaller than the internal peripheryof said socket for passing therethrough upon dismantling of said pump.10. A boiling water reactor plant as set forth in claim 8 furthercomprising at least one duct in said socket bypassing said turbine forsupplying feed water into said water chamber.
 11. A boiling waterreactor plant as set forth in claim 8 further comprising means foradmixing feed water supplied through said socket with a circulating flowof water in said pump.
 12. A boiling water reactor plant as set forth inclaim 11 wherein said pump has a plurality of diffuser blades on aninlet side thereof, and said admixing means includes bores within eachblade extending outwardly thereof into the circulating flow, said boresbeing connected to said duct in said socket for discharging feed waterfrom within said blades into the circulating flow.